I can tell you, character development is one of the hardest, but most important parts of your story. Good, realistic, and relatable characters can sell your story in an instant (JK Rowling, anybody?), and bad characters can kill it. There are a few thingsa you should remember when designing your character and when they speak.

Part 1: Character Development

First is actually developing the character. The first thing to do is create their past. Try and find a way to make their past shape who they are. However, that doesn't mean that a given past event results in a given trait. Different people respond differently to circumstances.

A good example that I haven't talked about in my novel, The Elements, would be Cerulea and Crystal. Their father died when they were 10. They responded differently: Crystal began looking at the positive side of things and being optimistic, because she couldn't stand being saddened by his death. Cerulea did everything in her power to avoid loving a person ever again. Just find a way to reasonably link the trait to any events.

Next would be making them round. For those of you who don't know what that means, it basically means that the character isn't just one, plain character with a few simple traits. Even a timid person opens up sometimes, which has proven difficult for me in The Elements. Cerulea was made as a closed in person, but when she opened up to the others, I had nothing. Every character needs two similar personalities. One could say the second is a back-up: When they aren't the first for whatever reason, the second comes out. When Cerulea opens up, for example, her second personality, the kind, conflict avoiding side comes out.

Part 2: Dialouge

Finally, dialouge. First is coming up with quantity. Let's say I'm having a scene with Liat, Crystal, and Tenion. Crystal doesn't talk much, even when she opens up, which we must consider. Tenion is a serious chatter box, so he'll talk a lot. Liat is rather in the middle.

When you determine who the next speaker will be, consider four things:

1) What will be said or asked. Just think about what information they are sharing or question they are asking. This will lay the groundwork for the dialouge

2) The circumstances. Naturally, one would speak differently in their house then when they're spying on an enemy.

3) Their personality and quirks. Consider things like an accent or if they are repetitive when they speak.

4) Make it realistic and work out contradictions. A person that is loud, but hiding from an enemy will naturally remain quiet. Consider the realism of the dialouge. One thing I do is say the line myself in the mood I intend it to be said, whether that be worried, excited, or sad. If it isn't realistic, you'll know it.

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Do that, and your novels and short stories will improve by leaps and bounds. Now, go develop that second side to your characters before they die because they're so board with the lousy* personalities you gave them.